When the use on a lot is single-family detached dwelling, single-family semidetached dwellings, two-family detached dwellings or two-family semidetached dwellings, and if two or more driveways of the same lot, any of which serve more than one dwelling, enter a public street right-of-way, the distance between the entrances of the driveways shall be at least 50 feet, measured between the inner edges of the driveway.